Pneumocystis jirovecii colonization in patients with systemic autoimmune diseases: prevalence, risk factors of colonization and outcome.

OBJECTIVES

To determine the rate and identify risk factors of Pneumocystis jirovecii (P. jirovecii) colonization among patients with systemic autoimmune diseases.

METHODS

We conducted an observational study in patients with systemic autoimmune diseases in an internal medicine department. Each week, five patients with systemic diseases were randomly selected for colonization screening. Patients complaining of recent respiratory symptoms were excluded. P. jirovecii PCR was performed on induced sputum samples. Univariate and multivariate logistic regression analyses of clinical and biological data were performed to determine predictors of Pneumocystis colonization. Pneumocystis pneumonia occurrence in P. jirovecii-positive PCR patients was recorded during a 1-year follow-up.

RESULTS

P. jirovecii was detected in 11/67 (16%) subjects. Comparing the features in P. jirovecii-positive and P. jirovecii-negative PCR patients, only male gender was significantly associated with Pneumocystis colonization. In multivariate analysis with regard to gender, the higher prevalence of P. jirovecii colonization in men was largely explained by higher daily CSs [odds ratio (OR) = 1.6; 95% CI 1.1, 2.3] and lower total lymphocyte level (OR = 0.9; 95% CI 0.8, 0.99). No P. jirovecii-positive PCR patient developed Pneumocystis pneumonia during the 1-year follow-up, but corticosteroid amounts were significantly lower at the end of follow-up than on inclusion.

CONCLUSION

This is the first study on P. jirovecii colonization in patients with systemic autoimmune diseases. We found a high prevalence of colonization and identified CS therapy and lymphocyte counts as risk factors for colonization. We recommend screening for P. jirovecii colonization in patients with systemic autoimmune diseases receiving immunosuppressant treatment. Further studies are needed to determine the role of subclinical colonization in disease transmission and the persistence of Pneumocystis colonization.